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已知圆C:x2+y2=1,点A(-2,0)及点B(2,a),从A点观察B点,要使...
已知圆C:x
2+y
2=1,点A(-2,0)及点B(2,a),从A点观察B点,要使视线不被圆C挡住,则a的取值范围是( )
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101230637560476541/SYS201311012306375604765006_ST/images0.png)
A.(-∞,-1)∪(-1,+∞)
B.(-∞,-2)∪(2,+∞)
C.(-∞,-
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101230637560476541/SYS201311012306375604765006_ST/0.png)
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101230637560476541/SYS201311012306375604765006_ST/1.png)
)∪(
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![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101230637560476541/SYS201311012306375604765006_ST/3.png)
,+∞)
D.(-∞,-4)∪(4,+∞)
考点分析:
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